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Al,
Again not a fair comparison and not exclusive
territory of the rotary. If your friend was flying a Cont/Lyc powered Velocity
like yours and his alternator crapped he could go down to the local parts store
and buy the same alternator/regulator you bought.
I'll grant you the overhaul cost and I'm with
you there. But then he bought a certified airplane and has to accept the baggage
that comes with it. Of course installing a new engine will increase the resale
value of his Bonanza quite a bit which makes the price a little less
painful.
By the way, where did you get the
over-voltage circuit? I'd like to incorporate that myself - seems like cheap
insurance.
Mike Wills
RV-4 N144MW
----- Original Message -----
Sent: Tuesday, March 03, 2009 8:18
AM
Subject: [FlyRotary] Re: Questions on
buying a rotary plane
Mark;
Good point on the
fuel cost. Here’s another that is fresh in my mind. I noticed a few weeks that
the voltage was fluctuating during flight, ranging about 1 ½ volts, and
hitting a high over 15.5 volts. I use the internal regulator, but
modified to use external field supply with a ‘crowbar’ circuit for
over-voltage protection. I decided to replace the regulator. Took the
alternator off, opened it up, got a replacement regulator at a local rebuild
shop for $38; back together on the plane, working fine. Meanwhile my
friends Bonanza is in for an annual. They decided the alternator wasn’t
putting out what it should – replacement cost: over $700.
His Continental
(520 I think) is past the 1750 recommended TBO. So he is debating between
factory reman at about $35,000, or new at about $45,000.
Yeah; I love my
rotary 20B.
Al
G
-----Original
Message-----
From: Rotary
motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mark Steitle
Sent: Tuesday, March 03, 2009 5:24
AM
To: Rotary motors in
aircraft
Subject: [FlyRotary]
Re: Questions on buying a rotary plane
I'll throw my 2 cents worth in
here. Regardinging fuel burn, I'm not overly concerned with bsfc,
although its not that bad if you're running EFI. What we're really
interested in is cost per mile. I have burned nothing but mogas in my
3-rotor Lancair. The last time I purchased fuel, it was
$1.65/gallon. My N/A 3-rotor burns between 10 and 11 gph at
around 20" MAP. So, it will cost me somewhere around $16.50 -
$18.15/hr to fly. Other Lancair ES's are running IO-540's, or some
derivative of the "540". From what I hear, they burn between 12 - 15
gph. With the cost of 100LL running around $4/gallon, that would
cost between $48 - $60/hr in fuel. So, figuring cost per mile,
I don't see how a Lycoming could come close to matching a
rotary. The fuel savings alone will more than cover the cost of an
overhaul.
And hope the Lycoming doesn't burn a
valve, or any number of other common ailments which can take a
serious bite out of your checkbook. Most of the things that break
on a piston engine aren't even present on the rotary. If it ain't there,
it can't break.
So, would I use a rotary if I were to do
it over, yes, absolutely!
On Mon, Mar 2, 2009 at 11:31 PM, William
Wilson <fluffysheap@gmail.com>
wrote:
I have not found
an accomodating A&P but I attribute that to the fact that I have not
looked yet. Given that I live in Seattle I am pretty sure I can find
one. Seattle is crawling (fluttering?) with homebuilt planes. If
anyone has suggestions, I am listening, but I had not started searching
yet.
Plan is not to take apart a perfectly good flying plane to change
the engine, but ideally to get one with a rotary in it already, or replace
only at overhaul time. In each case I save as much on the cheaper engine
as I would lose on resale value... and if the plane has the rotary in it to
start with, I get to pay the lower price up front too, which makes price
difference just plain better.
For efficiency what I said was that
homebuilt planes are more efficient than factory built, not that rotary are
more efficient than Lycoming, though in that case it should be quite
close. Bad fuel economy of rotary engine is overstated, economy is
comparatively bad at low power & RPM but at high power it is not bad at
all. As long as you are not turbocharged, you can run much leaner than a
piston engine, making up for less efficient combustion chamber shape.
Rotary BSFC in the lab has gone as low as .375 (for renesis), and .44-.46
measured in real world racing applications even with traditional type
engine. So I think I would not see a significant difference in fuel
economy between rotary and piston. Weight & drag of the plane it is
in will matter more.
In any case all advice is welcome, even dissenting
opinions ;)
I highly recommend you
check around to make sure you can find an A&P who will do a condition
inspection with the rotary engine installed BEFORE you commit. Many A&Ps
I've talked to dont want anything to do with Experimentals let alone an
engine that looks nothing like what they are used to. There's simply too
much potential liability (real or perceived) to go out on a limb like that.
The A&P who used to do the condition inspection on the RV-6A I used to
own (Lycoming powered) was willing to do it because the RV structure is
similar to typical spam cans. He wont have anything to do with wet layup
homebuilts (EZs, Cozys, etc...). He doesnt even like doing annuals on
Diamond aircraft with the Rotax 912/914 and they are
certified.
If you buy a flying
homebuilt that is Lyc or Continental powered, before you convert it to
rotary power seriously think about what you are doing to the resale value -
if you could ever sell it that is. My guess is that you'll give up at least
$10,000 in resale value, maybe much more. No big deal if you plan on keeping
it for life.
I dont know where you got
the idea that rotaries are more fuel efficient. Lycosaurs/Continentals
typically have BSFCs in the low .40s. The commonly accepted number for a
rotary is about .50. Some here seem to do better, others worse. With a grand
total of 2 hours on my rotary I cant say what my experience will be but hope
its close to the Lyc I used to fly.
Finally dont underestimate
the effort required to make the change. I started building my RV-4 in
late 1995. The airframe was essentially done in 2000. My first flight was
last month. Granted I took longer than many and much of the trouble came
from my desire to eliminate the cowl cheeks on an already cramped engine
compartment. But thats eight years of tinkering to get the engine installed
and running to the point where I had enough confidence in it to fly
it.
Not trying to discourage
you, but go into this with eyes wide open.
----- Original
Message -----
Sent:
Sunday, March 01, 2009 7:46 PM
Subject:
[Norton AntiSpam] [FlyRotary] Re: Questions on buying a rotary
plane
This is great
news. Thanks Charlie and Bob :)
On Sun, Mar 1, 2009 at 7:34 PM,
Charlie England <ceengland@bellsouth.net> wrote:
William Wilson
wrote:
I am in the market for a plane and
would prefer a rotary-powered, as I have lots of experience working with
rotary engines. As a bonus, homebuilt planes all seem to get about
twice as much fuel economy as factory built planes. So that is nice
too. I know there are a few rotary powered planes available for
sale, but not too many.
I have neither the time nor desire to build
my own plane, so my question is more about maintenance and inspections.
I'm not an official A&P and I don't know if I will be able to
find an A&P to work on a home built plane with a car engine in it!
I am happy to do engine maintenance, but am not entirely clear on
the legality of it, since I would not be the original
builder.
Similarly when it is eventually time for an engine
rebuild, would I be able to remove the engine, take it down to Atkins (who
are not far from me) and have them rebuild it, or rebuild it myself, and
then reinstall it, and find an A&P to just sign off on the
work?
Plan B is to buy whatever plane even if it has a Lycosaurus,
but when time for overhaul comes, get rid of the Lycoming and replace it
with a rotary. Thought in this case is to get the rotary tuned, a
little broken in and running on a stand in the hangar in advance, so that
when the time comes to do the swap it can be done with a minimum of
downtime. (I know it cannot really be tuned for altitude in this way
but it is better than nothing!). But again, the fact that I would
not be the original builder makes me worry about legalities. I have
heard that this has been done so question is more about the how.
I
do not really understand all the law involved and hopefully somebody here
can help. Thanks!
I can't speak with authority, but I
can speak from experience.
Experimental homebuilts can be
maintained or modified by anyone. No FAA blessings required. Annual
condition inspections must be performed by either the holder of the
'repairman's certificate' (only available to the builder of record) or by
the holder of an A&P ticket (no IA required).
Once the
airworthiness certificate is awarded, *anyone* can do any maintenance,
repairs, modifications etc desired. The post-modification requirements
vary somewhat from plane to plane depending on when the a/w was issued,
but in general terms, you notify the FAA in writing that major mods were
made, ask for a defined test area, make a log entry detailing the return
to 'phase one' testing, fly test flights for (typically) 5 hours, then
make another log entry saying that the plane has been tested with the mods
& is being returned to 'phase two' (normal operational)
status.
'Major modification' isn't clearly defined, but if you have
to ask, it's major. :-)
The availability of an A&P to sign off
condition inspections is all over the map (literally). It's never been a
problem for me, but in some parts of the country people can't find an
A&P who will sign off *any* homebuilt, no matter what engine. If
you have that problem, get to know the guys who sign off the crop
dusters in your area.
Hope that helps....
Charlie
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